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6<title>Using Qt Standard Dialogs</title>
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32<td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>Using Qt Standard Dialogs</h1>
33
34
35
36[ <a href="motif-walkthrough-2.html">Previous: Preparing to Migrate the User Interface</a> ]
37[ <a href="motif-walkthrough.html">Home</a> ]
38[ <a href="motif-walkthrough-4.html">Next: Using Custom QDialogs</a> ]
39<p> We start by using two of the <a href="dialogs.html">Qt Standard
40Dialogs</a>: <a href="qfiledialog.html">QFileDialog</a> and <a href="qmessagebox.html">QMessageBox</a>. Both of these classes
41provide useful static convenience functions.
42<p> <center><table cellpadding="4" cellspacing="2" border="0">
43<tr bgcolor="#f0f0f0"> <td valign="top">QFileDialog::getOpenFileName() <td valign="top">replacement for the <em>Open</em> dialog
44<tr bgcolor="#d0d0d0"> <td valign="top">QFileDialog::getSaveFileName() <td valign="top">replacement for the <em>Save As</em> dialog
45<tr bgcolor="#f0f0f0"> <td valign="top">QMessageBox::information() <td valign="top">replacement for <em>Page Delete</em> dialog
46<tr bgcolor="#d0d0d0"> <td valign="top">QMessageBox::warning() <td valign="top">replacement for <em>IO Error</em> dialog.
47</table></center>
48<p> Each of these functions takes a <em>QWidget *parent</em> argument. If we
49pass zero as the <em>parent</em> argument, then we will have dialogs that
50are centered on the screen, instead of being centered over our main
51window. We can have <a href="qmotifwidget.html">QMotifWidget</a> create our <tt>XmMainWindow</tt>, and we
52can then use this class as the parent for both <a href="motif-extension.html#Motif">Motif</a> dialogs and Qt
53dialogs.
54<p> We need to include the appropriate headers for QMotifWidget and
55<a href="qfiledialog.html">QFileDialog</a> in <tt>todo.cpp</tt>.
56<p>
57
58<pre></pre>
59<p> Next, we make a few modifications to how the application is
60initialized. We could initialize Xt/Motif and create the <tt>XtAppContext</tt> ourselves, but <a href="qmotif.html">QMotif</a> can do this for us.
61We also let <a href="qapplication.html">QApplication</a> open the connection to the X server. Next,
62we create a QMotifWidget, passing <tt>xmMainWindowWidgetClass</tt> as the <em>widgetclass</em> argument. We can now use the <a href="qmotifwidget.html#motifWidget">QMotifWidget::motifWidget</a>()
63function to access the Motif widget. The shell widget is created
64automatically by QMotifWidget. We use <tt>XtParent()</tt> to access it.
65The top-level window is now a QMotifWidget, which means we can use it
66as the parent for the Qt Standard Dialogs.
67<p> <pre></pre>
68<p> <h2> Replacing the <em>Open</em> and <em>Save As</em> Dialogs
69</h2>
70<a name="1"></a><p> First, we completely remove all use of the existing Motif file
71selection dialog. We remove the <tt>Xm/FileSB.h</tt> include, the global <tt>file_dialog</tt> variable, and the code to create the dialog. We also
72remove the <tt>PresentFDialog()</tt> callback function. None of this code
73is needed to use <a href="qfiledialog.html">QFileDialog</a>.
74<p> After removing the <tt>PresentFDialog()</tt> callback function, we need to
75make <em>Open</em> and <em>Save As</em> popup-menu callbacks call the <tt>Open()</tt>
76and <tt>Save()</tt> functions.
77<p> First we must change the declaration of these two functions.
78<p>
79
80<p> <pre></pre>
81<p> We also change the arguments to the callbacks. We pass the top-level
82<a href="qmotifwidget.html">QMotifWidget</a> as the <tt>client_data</tt> to these functions, since we will
83be using it as the parent for the QFileDialog.
84<p> <pre></pre>
85<p> <pre>
86 ...
87</pre>
88
89<p> <pre></pre>
90<p> Next, we modify the <tt>Save()</tt> function to use
91<a href="qfiledialog.html#getSaveFileName">QFileDialog::getSaveFileName</a>().
92<p> <pre></pre>
93<p> ... and the <tt>Open()</tt> function to use <a href="qfiledialog.html#getOpenFileName">QFileDialog::getOpenFileName</a>().
94<p> <pre></pre>
95<p> After we build the project, the application runs and operates as
96expected. The difference is that the <em>Open</em> and <em>Save As</em> dialogs
97now use <a href="qfiledialog.html">QFileDialog</a>.
98<p> <h2> Replacing the <em>Page Delete</em> and <em>IO Error</em> Dialogs
99</h2>
100<a name="2"></a><p> The <em>Page Delete</em> dialog is created and used in <tt>actions.c</tt>. We
101need to migrate this file to C++. We rename it to <tt>actions.cpp</tt>,
102modify the project file and regenerate the <tt>Makefile</tt>.
103<p> The changes required to make <tt>actions.cpp</tt> compile are minimal. We
104need to wrap more C header files and global variables in an <tt>extern "C"</tt> block.
105<p>
106
107<p> <pre></pre>
108<p> We need to forward declare the <tt>NewPage()</tt>, <tt>DeletePage()</tt>, <tt>EditPage()</tt> and <tt>SaveIt()</tt> functions so that the compiler generates
109the correct symbols for these functions.
110<p> <pre></pre>
111<p> We need to fix a single invalid pointer cast.
112<p> <pre></pre>
113<p> And we need to change the variable named <em>new</em> to <em>newstr</em> in the <tt>Trim()</tt> function.
114<p> We can now change the <tt>DeletePage()</tt> function to use
115<a href="qmessagebox.html#information">QMessageBox::information</a>().
116<p> First, we need to make sure we include the proper header for
117<a href="qmessagebox.html">QMessageBox</a>.
118<p>
119
120<pre></pre>
121<p> The code for <tt>DeletePage()</tt> looks like this:
122<p> <pre></pre>
123<p> At this point in the code, the page should be deleted. The code to do
124this is in the <tt>DoDeletePage()</tt> function. We move the contents of <tt>DoDeletePage()</tt> to this point and remove the <tt>DoDeletePage()</tt> function
125completely.
126<p> Next, we change <tt>todo.cpp</tt> to pass the top-level <a href="qmotifwidget.html">QMotifWidget</a> as the
127<tt>client_data</tt> tot he <tt>DeletePage()</tt> function.
128<p>
129
130<p> <pre></pre>
131<p> The <em>IO Error</em> dialog is created and used in <tt>io.c</tt>. We need to
132migrate this file to C++. We rename it to <tt>io.cpp</tt>, modify the
133project file and regenerate the <tt>Makefile</tt>.
134<p> The changes required to make <tt>io.cpp</tt> compile are minimal. We need
135to wrap more C header files and global variables in an <tt>extern "C"</tt>
136block.
137<p>
138
139<p> <pre></pre>
140<p> We need to forward declare the <tt>ReadDB()</tt> and <tt>SaveDB()</tt> functions
141so that the compiler generates the correct symbols for these
142functions.
143<p> <pre></pre>
144<p> The <tt>ParseNewLines()</tt> function needs to be converted to proper C++.
145<p> <pre></pre>
146<p> The <tt>PrintWithNewLines()</tt> function also needs to be converted to proper
147C++.
148<p> <pre></pre>
149<p> We can now change the <tt>ReadDB()</tt> and <tt>SaveDB()</tt> functions to use
150<a href="qmessagebox.html#warning">QMessageBox::warning</a>().
151<p> First, we need to make sure we include the proper header for <a href="qmessagebox.html">QMessageBox</a>.
152<p>
153
154<pre></pre>
155<p> The code for <tt>ReadDB()</tt> looks like this:
156<p> <pre></pre><pre>
157 ...
158</pre>
159
160<p> The code for <tt>SaveDB()</tt> looks like this:
161<p> <pre></pre><pre>
162 ...
163</pre>
164
165<p> After we build the project, the application runs and operates as
166expected. The difference is that the <em>Page Delete</em> and <em>IO Error</em> dialogs now use QMessageBox.
167<p> [ <a href="motif-walkthrough-2.html">Previous: Preparing to Migrate the User Interface</a> ]
168[ <a href="motif-walkthrough.html">Home</a> ]
169[ <a href="motif-walkthrough-4.html">Next: Using Custom QDialogs</a> ]
170<p>
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